Type alias IsStringLiteral<T, $O>

🎭 predicate

Validate if T is a string literal(s).

Example

type R = IsStringLiteral<string> // false
type R = IsStringLiteral<'a'> // true
type R = IsStringLiteral<`${number}`> // true

type R = IsStringLiteral<never> // false
type R = IsStringLiteral<unknown> // false
type R = IsStringLiteral<'a' | boolean> // boolean
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🔢 customize

Filter to ensure T is a string literal(s), otherwise returns never.

Example

type R = IsStringLiteral<string, { selection: 'filter' }> // never
type R = IsStringLiteral<'a', { selection: 'filter' }> // 'a'

type R = IsStringLiteral<never, { selection: 'filter' }> // never
type R = IsStringLiteral<unknown, { selection: 'filter' }> // never
type R = IsStringLiteral<'a' | boolean, { selection: 'filter' }> // 'a'
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🔢 customize:

Disable distribution of union types.

type R = IsStringLiteral<'abc' | 1> // boolean
type R = IsStringLiteral<'abc' | 1, { distributive: false }> // false
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🔢 customize:

Check if T is exactly a string literal, excluding template literals.

type R = IsStringLiteral<'${number}'> // true
type R = IsStringLiteral<'${number}', { exact: true }> // false
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🔢 customize

Use unique branch identifiers to allow precise processing of the result.

Example

type R = IsStringLiteral<'abc', $IsStringLiteral.$Branch> // $Then
type R = IsStringLiteral<string, $IsStringLiteral.$Branch> // $Else
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